Electrical installation



Patented May 26, 1936 2,042,421

UNITED STATES PATENT oFFIcE ELECTRICAL INSTALLATION Ralph W. Atkinson,Perth Amboy, and Albert M.

Hagen, Woodbridge, N. 3., assignors to General Cable Corporation, NewYork, N. Y., a corporation of New Jersey Application December 12, 1934,Serial No. 757,242

8 Claims. (Cl. 138-29) This invention relates to electricalinstallations 6 and l. Conveniently the cylindrical casing and andequipment, and more particularly to such inthe end members are made ofmetal and are stallations and equipment which include insula- Weldedtogether at their contacting surfaces. In tion of a liquid characterwhich is to be kept free the illustrative embodiment the connector 4com- 5 of moisture, air and other gases. It is an object municates withthe container through an open- 5 of the invention to provide an improvedmeans ing in the upper end member 8.

for maintaining the integrity of the insulation. Within the container ofthe illustrative em- Other objects and advantages of the inventionbodiment is a cylindrical wall 8 slightly smaller in will appearhereinafter. diameter and of less length than the casing 5.

10 The invention will be best understood from the This cylindrical wallis secured to the container, 10

following description when read in the light of concentricallytherewith, with a fluid-tight joint the accompanying drawingillustrating a specific adjacent the lower end of the container, andconembodiment of the invention. In the drawing: venient y y be Welded atits lower end to the Fig. 1 shows in vertical section a reservoir forend member 1. Thus there is provided a thin liquid insulation connected,by way of example, annular Space between the casing 5 d e Wal 15 with acable joint; and 8 for a portion of the length of the container.

2 shows to enlarged scale the valve for In the drawing this annularspace is shown controlling the flow of liquid insulation into and w atexaggerated in t k s mer ly for out of the reservoir. purposes ofillustrating the construction.

In electrical installations and equipment For reinforcin t W and forOther 20 which include Within a confining wall a body of reasons whichwill appear hereinafter, the upper insulation of a liquid character, forexample an and 0f the Cylindrical Wall 3 desirably is Closed oil-filledcable, it is desirable to provide means to with a flang d member 9, theflange around its accommodate for the expansion and contraction ute e env ni tl bein We d d to the of the insulating material withoutpermitting pp end of the Wall end mber 9 also 25 ingress of air andmoisture, and without the foras a pwa y e i entra y located mation ofvoids or gas spaces in the insulation. ge 10 defin ng an opening llthrou the To further this end it is desirable that this member 9-Meunted Within the container, b ve means continuously maintain pressureon the inthe e d member is an inverted D p d sulating material. As usedherein the expression member comprisin in e u at e bed liquid insulationincludes any insulating mament, a cylindrical wall !2 extendingdownwardterial which in the course of service manifests 1y nto t eannular Space formed w n he characteristics of fluidity. Ordinarily theliquid casing 5 and the cylindrical wall 8, and a flanged insulationwill be an oil, and conveniently may end member I3, conveniently weldedto the upper be so described. end of the cylindrical wall I2. 35

Referring to Fig. l of the drawing, two cable The inverted cup shapedmember is free to lengths 3| are united within a joint casing 32 movevertically within the container, and desirwhich is connected fluid-tightat its ends to the able means are provided for accurately guidingsheaths of the cable lengths, as by means of the cup shaped member inits vertical movement wiped joints. The confined space within the toprevent contact between the wall I2 and the 40 joint casing 32surrounding the united cable ends casing 5 or the Wall 8, therebyreducing frictional ordinarily is filled with a liquid insulation,usualresistance to movement of the cup shaped memly in direct continuitywith the insulation in one her. In the illustrative embodiment thisguidor both of the connected cable lengths. ing means comprises a guiderod I4 depending The joint casing 32 is connected by means of from andsecured centrally of the end member 45 a pipe 33 and the connector 4with a variable oa- 13. This guide rod l4 passes downwardly throughpacity, fluid-tight container or reservoir conthe opening H in the endmember 9 into a guide taining a body of liquid insulation, and havingsleeve l5 conveniently secured at its lower end means for exertingpressure on the liquid into the end member 1. Rotation of the cup shaped5O sulation. In the illustrative embodiment a conmember within thecontainer may be prevented, fined. body of gas under pressure is reliedupon if desired, by providing the guide rod M with a for exertingpressure on the liquid insulation, key slot l6 and the guide sleeve 15with a set and the container comprises a vertically arranged screw II,the inner end of which enters the key cylindrical casing 5 closed at itsupper and lower slot I6.

ends, respectively, by the flanged end members It will be apparent fromthe description thus 55 far that the inverted cup shaped member is freeto move vertically within the container, such movement being accuratelyguided to insure the maximum freedom of movement. As shown in theaccompanying drawing, the cup shaped memher is nearly at the lowestpoint of its vertical movement. Continued downward movement of the cupshaped member will be halted when its end member l3 engages the flangeIE on the member 9. By suitably dimensioning the parts, this engagementdesirably will occur before the lower end of the cylindrical wall l2engages the bot tom of the container.

Within the annular space between the container wall 5 and thecylindrical wall 8, and surrounding the depending wall 52 of theinverted cup shaped member is a body 23 of liquid which is heavier thanthe insulating liquid. This liquid, for example mercury, constitutes aseal between the lower edge of the invert-ed cup shaped member and thecontainer wall 5, and divides the container into two chambers comprisingthe gas and the liquid insulation compartments. In the illustrativeembodiment the upper compartment contains the liquid insulation and thelower compartment contains gas under pressure, but this arrangement maybe reversed if desired.

Since the inverted cup shaped member is free to move vertically withinthe container, the pres sure on the liquid insulation in the upperportion of the container normally will be substantially the same as thepressure on the gas in the lower portion of the container. There beingno material difference in these pressures, the mercury or other liquid23 will function as a seal between the bodies of gas and liquidinsulation, normally preventing all contact therebetwcen. As the volumeof liquid insulation within the container varies, because of changingconditions of service in the electrical installation, the pressure onthe gas within the container will vary, but the pressure on both sidesof the inverted cup shaped member will always equalize.

Desirably a valve i8 is provided for the oil outlet pipe which is closedautomatically as the inverted cup shaped member approaches the upperlimit of its range of movement. This valve prevents passage of themercury or other sealing liquid and the gaseous pressure medium into theelectrical installation or equipment 'in the event that the reservoir isemptied of its liquid insulation.

The valve may be secured to the connector 4 in such a manner that itwill be closed as the inverted cup shaped member moves upwardly againstit. Or, as shown in Fig. 2, the lower part of the connector 4 may serveas the valve seat, and the valve closure member may be secured on top ofthe inverted cup shaped member.

Centrally secured on top of the end member I3 is a low spider or yoke 4%Secured on the upwardly spread arms of this spider is a plate 4| whichcloses the opening to the connector 4 when the inverted cup shapedmember is moved to its upper limit. Conveniently a gasket 32 of oilresistant material insures a tight closure. The parts are proportionedso that as the reservoir empties of liquid insulation the valve closesbefore any of the sealing liquid is forced out of its channel. To takecare of any small leak through the Valve 18 some movement of the cupshaped member may be permitted as by the use of a helical spring betweenit and the valve, or by making the spider 43 of elastic material. Y

When the flow of liquid insulation rvers esthe by pass valve 43, hingedto the plate 4! and normally held in closed position by a spring 44, isforced open by the pressure. This opening of valve 43 permits return ofliquid insulation into the reservoir until the pressure is sufiicient toforce the inverted cup shaped member downwardly to open the main valve,whereupon the valve 43 again closes.

Ifa valve is not provided to close the outlet to the pipe 33 as theinverted cup shaped member approaches the upper limit of its range ofmovement, a stop should be provided to prevent the members l3 and 6being forced directly together. Such a stop functions to halt upwardmovement of the floating cup shaped member while there still issuflicient space so that if all of the liquid insulation were drainedout of the container there would be no chance of the mercury followingthe oil into the cable or other electrical installation. That is, theresidual space between the members l3 and 6 Would be able to retain asmuch of the mercury as could be forced out of the annular groove by thegas pressure.

Means are provided for supplying liquid in-- sulation to the upperportion of the container, and conveniently this means may take the formof a valved grease plug l9 secured in an opening in the upper end member6. This grease plug desirably is protected against dirt and moisture bya cap 20.

Gas under pressure conveniently is supplied to the lower portion of thecontainer through a tire valve 2| secured in an opening in the lower endmember 1. This valve may be protected against dirt and moisture by a cap22.

Desirably means are provided for observing the amount of liquidinsulation contained within the reservoir at any time. In theillustrative embodiment a window 24 is provided in the casing 5intermediate its ends. Conveniently this window is provided with a pane25 of glass held in place by the rim 26. Gaskets are provided at theedge of the glass to prevent breakage and to provide a fluid-tight seal.Pressure on the rim 25 against the glass conveniently is obtained bymeans such as the screws 28 and the nuts 29.

The mercury which acts as a seal between the liquid insulation and thebody of gas is much heavier than the liquid insulation. The level wherethe insulating liquid and the mercury meet may be readily observedthrough the glass 25. As the amount of insulating material within thecontainer increases, the mercury level will rise in the glass, and asthe volume of insulating material decreases, the mercury level willfall.

This construction lends itself readily to the use of 'an alarm andsignal system for giving electrically an indication of the amount of oilwithin the reservoir. The mercury is itself a conductor, and can be usedto complete electrical circuits through contacts mounted in the outerwall of the container at or near the extreme limits of movement in eachdirection.

A window similar to the window 24, or a gauge glass, notshcwmmay beprovided in the bottom of the "reservoir to permit inspection fordetermining whether any of the liquid insulation has been forced throughthe mercury seal. Any such liquid may be withdrawn through the valve 2I.

If the insulating liquid and the sealing liquid are of such natu "esthat the latter may dissolve or evaporate slightly into the former,means desirably are provided to remove these traces of sealing liquidfrom the insulating liquid. Where 7 5 ing a screen or mass 35 of metalfor which the mercury has a high affinity. For example, 35 may comprisecopper, brass or lead W001.

The reservoir thus far described is comparatively simple and inexpensiveto manufacture. Since there are no thin flexible metal diaphragms ortubes such as have been employed heretofore in reservoirs for this typeof service, all danger of contact between the insulating liquid and thegaseous pressure medium due to failure of the metal is eliminated.

Furthermore, the construction is comparatively foolproof as regardshandling during installation. There is no necessity for supplying themercury to the reservoir until the reservoir has been mounted in itsplace of installation, as by means of brackets 39. However, if themercury is supplied to the reservoir before it has been mounted in itsfinal position, there is practically no danger of permanent displacementof the mercury during the handling of the reservoir.

If the reservoir is tipped sufficiently the seal between the gas and theliquid insulation compartments will be broken. But when the reservoir isagain returned to its normal position the mercury will at once fall backinto the annular recess between the casing 5 and the wall 8,re-establishing the seal. By reason of the shapes of the members 9 andI3, and the provision of the flange it on the member 9, it ispractically impossible for any of the mercury to escape into the bottomof the container.

If during installation or service there should be a sudden surge ofpressure on the insulating liquid sufiicient to blow some of theinsulating liquid through the mercury seal, the mercury seal wouldimmediately re-establish itself, and such oil blown through the sealwould merely float on top of the mercury between the members 9 and R3,or if sufiicient in quantity would flow through the flanged opening llinto the bottom part of the reservoir.

It will be understood that the invention may be variously modified andembodied within the scope of the sub-joined claims.

We claim:

1. The combination with a length of sheathed, oil-filled cable, of meansfor preserving the integrity of the cable insulation under changingconditions comprising a fluid-tight container, an inverted cup shapedmember smaller and of less length than the container within andconnected fluid-tight at its open end to the lower end of the container,said cup shaped member having a flanged opening through its closed end,a second inverted cup shaped member within the con- Itainer having itswall extending downwardly into the annular space formed between thefirst mentioned cup shaped member and the wall of the container, meansfor supplying gas under pressure to the container on one side of thesecond mentioned cup shaped member, means for supplying oil to thecontainer on the other side of the second mentioned cup shaped member,means connecting the container with the cable permitting the flow of oiltherebetween, and a body of liquid heavier than the oil within the saidannular space constituting a seal between the gas and the oil whilepermitting movement of the second mentioned cup shaped member as thevolume of oil within the container varies.

2. The combination with a length of sheathed, oil-filled cable, of meansfor preserving the integrity of the cable insulation under changingconditions of service comprising a fluid-tight container having formedwithin its lower part an annular space, an inverted cup shaped memberwithin the container having its wall extending downwardly into the saidannular space, means for supplying gas under pressure to the containeron the under side of the cup shaped member, means for supplying oil tothe container on the upper side of the cup shaped member, meansconnecting the container with the cable permitting the flow of oiltherebetween, and a body of liquid heavier than the oil within the saidannular space constituting a seal between the gas and the oil whilepermitting movement of the cup shaped member as the volume of oil withinthe container varies.

3. The combination with an electrical installa tion which includes abody of liquid insulation within a confining wall, of means forpreserving the integrity of the insulation comprising a verticallydisposed, fluid-tight cylindrical container, a cylindrical wall slightlysmaller in diameter and of less length than the container within andconnected fluid-tight at its lower end to the lower end of thecontainer, a cover secured fluid-tight to the upper end of saidcylindrical wall, an inverted cup shaped member within the containerhaving its wall extending downwardly into the annular space formedbetween the said cylindrical wall and the wall of the container, meansfor supplying gas under pressure to the container on one side of the cupshaped member, means for supplying liquid insulation to the container onthe other side of the cup shaped member, means connecting the containerwith the said installation permitting the flow of liquid insulationtherebetween, and a body of mercury within the said annular spaceconstituting a seal between the gas and the liquid insulation whilepermitting movement of the cup shaped member as the volume of liquidinsulation within the container varies.

4. The combination with an electrical installation which includes a bodyof liquid insulation within a confining wall, of means for preservingthe integrity of the insulation under changing conditions comprising afluid-tight cylindrical container, a cylindrical wall smaller indiameter and of less length than the container within and connectedfluid-tight at one end to the lower end of the container, an invertedcup shaped member within the container having its wall extendingdownwardly into the annular space formed between the said cylindricalwall and the wall of the container, means for supplying gas underpressure tothe container on one side of the cup shaped member, means forsupplying liquid insulation to the container on the other side of thecup shaped member, means connecting the container with the saidinstallation permitting the flow of liquid insulation therebetween, abody of liquid heavier than the liquid insulation within the saidannular space constituting a seal between the gas and liquid insulationwhile permitting movement of the cup shaped member as the volume ofliquid insulation within the container varies, and means for preventingflow of the sealing liquid out of the said annular space into theelectrical installation under abnormal operating conditions.

5. A variable capacity reservoir for supplying liquid insulation underpressure to an electrical 75 installation comprising, in combination, afluidtight cylindrical container, a cylindrical wall slightly smaller indiameter and of less length than the container within and connectedfluidtight at one end to the lower end of the container, an inverted cupshaped member within the container having its wall extending downwardlyinto the annular space formed between the said cylindrical wall and thewall of the container, means for supplying gas under pressure to thecontainer on one side of the cup shaped member, means for supplyingliquid insulation to the container on the other side of the cupshapedmember, a body of mercury within the said annular space constituting aseal between the gas and the liquid insulation while permitting movementof the cup shaped member as the volume of liquid insulation within thecontainer varies, and a window in the wall of the corn tainer permittingobservation of the mercury level to indicate the volume of liquidinsulation within the container.

6. The combination with a length of sheathed, oil-filled cable, of meansfor preserving the integrity of the cable insulation under changingconditions of service comprising a fluid-tight container having formedwithin its lower part an annular space, an inverted cup shaped memberwithin the container having its wall extending downwardly into the saidannular space, means for supplying gas under pressure to the containeron one side of the cup shaped member, means for supplying oil to thecontainer on the other side of the cup shaped member, means connectingthe container with the cable permitting the flow of oil therebetween, abody of liquid heavier than the oil within the said annular spaceconstituting a seal between the gas and the oil while permittingmovement of the cup shaped member as the volume of oil within thecontainer varies, valve means for controlling the flow of oil betweenthe container and the cable, and means for closing said valveautomatically when the quantity of oil within the container reaches apredetermined minimum.

'7. The combination with a length of sheathed,

oil-filled cable, of means for preserving the in-* tegrity of the cableinsulation under changing conditions of service comprising a fluid-tightcontainer having formed within its lower part an annular space, aninverted cup shaped member within the container having its wallextending downwardly into the said annular space, means for supplyinggas under pressure to the container on one side of the cup shapedmember, means for supplying oil to the container on the other side ofthe cup shaped member, means connecting the container with the cablepermitting the flow of oil therebetween, a body of liquid heavier thanthe oil within the said annular space constituting a seal between thegas and the oil while permitting movement of the cup shaped member asthe volume of oil within the container varies, and means associated withsaid annular space for causing the sealing liquid to return to theannular space and re-establish the seal following any surge of pressurewhich temporarily may have broken the seal.

8. The combination with a length of sheathed, oil-filled cable, of meansfor preserving the integrity of the cable insulation under changingconditions of service comprising a fluid-tight container having formedwithin its lower part an annular space, an inverted cup shaped memberwithin the container having its wall extending downwardly into the saidannular space, means for supplying gas under pressure to the containeron one side of the cup shaped member, means for supplying oil to thecontainer on the other side of the cup shaped member, means connectingthe container with the cable permitting the flow of oil therebetween; abody of liquid heavier than the oil within the said annular spaceconstituting a seal between the gas and the oil while permittingmovement of the cup shaped member as the volume of oil within thecontainer varies, and filter means in the connection between thecontainer and the cable for removing from the oil any of the sealingliquid which may have been dissolved in the oil.

RALPH W. ATKINSON. ALBERT M. HAGEN.

